Cartilage, which is a heterogeneous tissue, can be classified as either articular or epiphyseal/physeal. Disturbances in cartilage structure and function are seen in congenital, infectious, traumatic, degenerative and neoplastic conditions. Biological repair of focal articular cartilage defects has generated great interest, yet some of the variables of this process have not been precisely defined (see, e.g., Brittberg et al., New Engl. J. Med., 331:889-895, 1994; and Mankin, New Engl. J. Med., 331:940-941, 1994). Such variables include the biochemical and biomechanical properties of the repair tissue itself and also its bonding with adjacent cartilage and bone.
The morphogenetic scaffold to which chondrocytes may attach and form matrix is one of the variables that have effects on the repair tissue. Materials that have been used as the scaffold include collagen gel (Fujisato et al., Biomaterials, 17:155-162, 1995; Hansen et al., Clin. Orthop., 256:286-298, 1990; Mizuno et al., Exp. Cell. Res., 227:89-97, 1996; Nixon et al., Am. J. Vet. Res., 54:349-356, 1993; Sams et al., Osteoarthr. Cartil., 3:47-59, 1995; Sams et al., Osteoarthr. Cartil., 3:61-70, 1995), fibrin glue (Hendrickson et al., J. Orthop. Res., 12:485-497, 1994; Homminga et al., Acta Ortopedica Scandinavica, 64:441-445, 1993; Tsai et al., J. Formosan Med. Assoc., 3(Suppl):239-245, 1993), polyglycolic acid (Freed et al., Biotechnology, 12:689-693, 1994; Vacanti et al., Am. J. Sports Med., 22:485-488, 1994), polyethylene oxide gel (Sims et al., Plast. Reconstr. Surgery, 98:843-850, 1996), alginate gel (Van Susante et al., Acta Ortopedica Scandinavica, 66:549-556, 1995), carbon fiber pads (Brittberg et al., Clin. Orthop., 326:270-283, 1996) and xenogeneic matrix (Caruso et al., J. Orthop. Res., 14:102-107, 1996).
Isolated and cultured chondrocytes embedded in these various scaffolds have been used for filling and repairing articular cartilage defects in chicks (Itay et al., Clin. Orthop., 220:284-303, 1987), rabbits (Grande et al., Anatomical Records, 218:142-148, 1987; Grande et al., J. Orthop. Res. 7:208-218, 1989; Wakitani et al., J. Bone Joint Surg. [Br.], 71:74-80, 1989), dogs (Shortkroff et al., Biomaterials, 17:147-154, 1996), and horses (Hendrickson et al., supra; Sams et al., Osteoarthr. Cartil., 3:47-59, 1995; Sams et al., Osteoarthr. Cartil., 3:61-70, 1995).
Complete repair of partial defects of cartilage implies side-to-side joining of cartilaginous matrices. While such joining has been investigated in several ways (Hunziker et al., Trans. Orthop. Res. Soc., 17:231, 1992; Reindel et al., J. Orthop. Res., 13:751-760, 1995; Wolohan et al., J. Orthop. Res., 9:180-185, 1991), options for accomplishing this still need to be expanded.